Preparation of branched chain hydrocarbons



uuirso stares PATENT} orrice PREPARATION or BRANCHED CHAIN HYDROCABBONSRobert E. Burk, Cleveland Heights, Ohio, assignor to The Standard OilCompany, Cleveland, Ohio,

N Drawing. Application April 18, 1942,

. Serial No. 439,543

2 Claims. lCl. 260-45835) In the common procedure of catalyticisomeriplehydrogen bromide, hydrogen chloride, hydrozation there isconsiderable side reaction of gen fluoride; and these may be in liquidor gasbreaking up of molecules or cracking. This ineous state. Pressuresup to 200 pounds per terferes with the production of the desir 'd kindsquare inch maybe applied in the reaction Zone of hydrocarbons, and alsorepresents a 'corre- 5 with the halide inthe gaseous tate. When thespending amount of waste of material." I have hydrogen halide ismaintained as a-liquid suffifound that if isomerization be carried firstto only eierlt Pressure is d to pr s r h liq id a slightly branchedcondition and an isomer be phase. An especially effective catalyst is aliquld iractioned out relatively clean from the reaction EF -El 'scatalyst, the partial pressure of boron mixture, th'is clean out can bethen isomerized fluoride being 50 to 550 pounds per square inch,

quite drastically without cracking. Difierent p a ly 150 po ndequilibrium conditions are involved thus stage- The operatingtemperatures in general desirwise, instead of in the customaryrun-through a y e 1 n r C. Preferably y y with a starting material, andthe usual cracking be low ordinary temperature and in the range loss maybe obviated, and desired isomer prod- 15 011 n to minus 25 uctsbeobtained. Where desired, isobutane may be present, 1-10 To theaccomplishment of the foregoing and 111015, Preferably 2 3 mole Hydrogenm y d related ends, the invention, then, comprises the sir'ably also beP s features hereinaiter fully described, and particrlhe hydrocarbons tobe treated are subjected ularly pointed out in the claims, the followingto the aforedescribed conditions for a time dedescription setting forthin detail certain illuspending on the temperature, the part ar omtrativeembodiments of the invention, these being p sit n of the a ys t c v tthem to indicative however, of but a few of the various lightly branchedhydrocarbons. Then, the halways in which the principle of the inventionmay ide catalysts are removed, such as by freezing be employed. out, orby distillation or other desiredway, and As raw material, hydrocarbonswhich it is dethe hydrogen hal de m y b removed by releassired toisomerize, in general may be applied. i s P s neutralizing, 6110- T n te P od- The light hydrocarbons, as of live to eight carbon lets arefractionated o Separate the Slightly atoms are especially applicable.Naphthas may branched hydrocarbons, a d slleh thus in relabe thustreated. Ihese are desirably fractiontively e rm ar then subjected tothe aforet t t corresponding to hydrocarbons 0 described conditions toisomerize them into more a given number of carbon atoms which are thenhighly branched hydreeerbenfi- Where desired, isomerized separately. Thehydrocarbons to be t product y be then fractionated, and arelaisomerized in the first step or the operation may tively u branchedisomer y be a n furbe normal saturated hydrocarbons. Any conthel l t0the is at n t, source of hydro arbon may be used As an example: N-hexaneis treated with 10 mol ever. In some cases it is desirable to start withcent of A1311 P1115 h temperature slightly branched hydrocarbons. Wherethe hymg not higher h o and Preferably the drocarbon 00115 or rawmaterial contain unsa Operation being Started at mlml 2 C Atter uratedand aromatic hydrocarbons in addition to about 130 hours, depending uponthe p ec se temparaffin hydrocarbons, these may be removed, forpetetlll'ee maintained, the produ t co ains example by extracting withselective solvents or something over half isomers, 2-methyl pentane byreacting with halides for that purpose. being largely predominant Omeane is As catalysts, the halide catalysts in general @150 formed eproduct s fr ti nated, and may be employed. Advantageous are thealumithe l p he ou i sublected to 10 mol num halide catalysts, such asaluminum chloride, p n of aluminum m de a yd o n br aluminum bromide, orcomplexes formed by th mide at about minus 11 C. for about 217 hours.halides with hydrocarbons, or alkyl halides may he p c is m ly more hi hy isom rized be used; also other halides such as acid-acting hexanes,specially 3-methyl pentane, and smallhalides of zinc, iron, arsenic,antimony, tin, 5 er amount of 2,3-dimethyl butane. These may boron, etc.Mixtures of such catalysts are 'debe fractionated'out and again beseparately subsirable in some instances. The amount of catajected to thehalide catalyst for further isomerizlyst may be 1 to 10 mol per centbased on the ation.

hydrocarbon. It is desirable to promote the hal- As another example:3-methyl pentane is treatide catalyst by a hydrogen halide, as forexamed at minus 11 C. with 10 mol per cent AlBI's As another example:2,3dimethyl butane orm more highly branched iso e t eat d a in t f e oinexample yields a p process for converting normal to slightly notcontaining 76.4 per cent of isomeric hexanes, branched hydrocarbons tohighly branched iso- 2 per cent being neohexane. No isobutane is mers bya unitary two-stage process, which comformed, and only 0.1 per cent ofisopentane. prises subjecting hydrocarbons having 5 to 8 carther modesof applying the principle of the bon atoms-closely fractionated tocontain priinvention may be employed, change being made marily normal toslightly branched parafiinic hyaS ards the details described, providedthe 15 drocarbons of the same number of carbon e equivalent of such beemploy d catalyst promoted by hydrogen halide at a tem thereforeparticularly point out and distinctperature below ordinary temperatureto form 1soy aim' as my invention: mers slightly more branched than saidstarting A process for convelting normal to slightly 20 hydrocarbons,separating the so-formed slightly branched hydrocarbons to highlybranched iso branched isomers from the remaining hydrocarmers by aunitary two-stage process, which com bons and subJectmg said separatedisomers to prises subJectmg hydrocarbons having 5 to 8 car furt erisomerization W1 h an alummum halide on atoms-closely fractionated tocontain pncatalyst promoted by a hydrogen halide at a tern marily'normalto slightly branched parafiinic hy- 5 perat ure below ordinarytemperature to form drocarbons of the same number of carbon more highlybranched isomers. atoms-t0 isomerization with a halide catalyst atROBERT E. BURK.

